1. Technical Field
The present invention relates to a valve unit which is provided in the middle of a flow path and opens/closes the flow path and a liquid ejecting apparatus having the valve unit.
2. Related Art
In a liquid ejecting apparatus or the like, a valve unit, such as a self sealing valve, which adjusts a liquid supply pressure in such a manner that the valve unit opens/closes a flow path is provided in the middle of the flow path through which liquid is supplied from a storage unit for storing the liquid to a liquid ejecting head for ejecting the liquid.
In the valve unit, a valve is opened in such a manner that a valve body is opened when a pressure on a downstream side becomes a negative pressure (a negative pressure relative to atmospheric pressure), and thus the liquid is supplied from an upstream side to the downstream side. Specifically, the valve body is provided in a communication hole (an inlet) which causes an accommodation chamber connected to an upstream flow path to communicate with a pressure adjustment chamber connected to a downstream flow path. In addition, a diaphragm is formed on one side surface of the pressure adjustment chamber, using a flexible film. Therefore, when the diaphragm is flexibly deformed in accordance with a pressure difference between a pressure of the liquid in the pressure adjustment chamber and atmospheric pressure, the communication hole (the inlet) is opened/closed by moving the valve body (for example, see JP-A-2008-230196).
However, the liquid which flows into the pressure adjustment chamber through the inlet is likely to flow, with passing through the shortest distance, to the outlet through which the pressure adjustment chamber is connected to the downstream flow path. Thus, in an area apart from a straight line connecting the inlet and outlet, the liquid stagnates, particularly, in a side opposite to the outlet side, on a line connecting the inlet and outlet. As a result, foreign matter, such as dirt and air bubbles, in the liquid or components in the liquid are likely to remain in the area described above.
For this reason, a valve unit in which a liquid flow is switched by modes switchable between a first mode in which a first flow path is formed in a state where a film does not come in contact with a wall portion in the pressure adjustment chamber and a second mode in which a second flow path is formed in a state where the film comes in contact with the wall portion, and thus stagnation of the liquid is suppressed has been proposed (for example, JP-A-2012-158002).
However, when wrinkles are formed on the film, due to heat during a film adhesion, it is difficult to perform a proper film adhesion for satisfying a condition in which there can be switching of modes between the first mode (the first flow path) and the second mode (the second flow path) disclosed in JP-A-2012-158002, when considering the convex and concave shapes of the wrinkles. Therefore, there is a problem in that it is difficult to control a switching operation (switching the abutment state between the film and a wall portion) between the first mode (the first flow path) and the second mode (the second flow path). When the switching operation between the first mode (the first flow path) and the second mode (the second flow path) is not properly performed, there is a concern that a supply pressure adjustment may not be properly performed because, for example, the film abuts on the wall portion during a supply pressure adjustment, and thus a force applied from atmospheric pressure to the film is transmitted to the wall portion and a force applied to a valve is reduced.
The problem described above is not limited to a valve unit intended to be mounted on a liquid ejecting apparatus, represented by an ink jet type recording apparatus, but is shared by a valve unit intended to be mounted on other apparatuses.